This invention relates to a crane, in particular a telescopic crane, with a frame suspended on the load hook for taking up a special load, in particular for taking up a rotor blade of a wind turbine
During the assembly of wind turbines, the rotor blades must be mounted at a great height. For this purpose, truck cranes or crawler cranes preferably are used. The rotor blade to be mounted has a large rotor surface and consequently a large surface exposed to the wind. For mounting the rotor blade at the corresponding wind turbine a sufficiently precise adjustment of the rotor blade taken up is required at the mounting height.
For this purpose it is already known from the prior art to take up the rotor blade by means of a frame. The same is suspended on the load hook of the hoisting cable and takes up the rotor to be mounted in the corresponding receptacle.
In DE 20 2006 015 189 U1 it is proposed for example to attach the rotor blade to the two guy cables of the Y-guy of the main boom via two control cables and secure the same against rotation. A disadvantage of the proposed solution consists in that the guy cables extend far away from the longitudinal axis of the main boom. Consequently, the forces in the horizontally extending control cables considerably influence the guying forces of the Y-guy and reduce the lifting capacity of the crane.
Furthermore, constructions are known in which in the region of the boom foot two additional winches are mounted, whose cables extend in parallel in direction of the boom head. The receptacle for the rotor blade is connected with the tensioned cables via two control cables.
A disadvantage of this known solution on the one hand consists in that the winches and the cables constitute an additional equipment which involves both weight and costs. In addition it is required to tension both cables independent of each other. The tensioning force introduced per cable exerts a load on the boom, since the resultant pressure load behaves like an additional load on the boom. Mounting two independent cables likewise leads to an additional side load of the boom, if one cable is loaded more.